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First Report of Sirosporium diffusum Causing Brown Leaf Spot on Carya illinoinensis in Brazil
2016; American Phytopathological Society; Volume: 101; Issue: 2 Linguagem: Inglês
10.1094/pdis-06-16-0820-pdn
ISSN1943-7692
AutoresTales Poletto, Marlove Fátima Brião Muniz, Elena Blume, Ricardo Mezzomo, Uwe Braun, S.I.R. Videira, Ricardo Harakava, Igor Poletto,
Tópico(s)Mycorrhizal Fungi and Plant Interactions
ResumoHomePlant DiseaseVol. 101, No. 2First Report of Sirosporium diffusum Causing Brown Leaf Spot on Carya illinoinensis in Brazil PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Sirosporium diffusum Causing Brown Leaf Spot on Carya illinoinensis in BrazilT. Poletto, M. F. B. Muniz, E. Blume, R. Mezzomo, U. Braun, S. I. R. Videira, R. Harakava, and I. PolettoT. Poletto, M. F. B. Muniz, E. Blume, R. Mezzomo, U. Braun, S. I. R. Videira, R. Harakava, and I. PolettoAffiliationsAuthors and Affiliations T. Poletto M. F. B. Muniz E. Blume R. Mezzomo , Department of Plant Pathology, Federal University of Santa Maria, Santa Maria, Brazil U. Braun , Martin-Luther-Universität, Institut für Biologie Bereich, Geobotanik und Botanischer Garten, Herbarium, Neuwerk 21, 06099 Halle (Saale), Germany S. I. R. Videira , CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands R. Harakava , Biological Institute of São Paulo, Brazil I. Poletto , Biochemistry and Biology Laboratory, UNIPAMPA, São Gabriel, Brazil. Published Online:14 Nov 2016https://doi.org/10.1094/PDIS-06-16-0820-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Pecan [Carya illinoinensis (Wangenh.) K. Koch] is economically important in the State of Rio Grande do Sul (RS), Brazil. During December 2013, brown leaf spot symptoms were observed in orchards and nurseries on up to 85% of the trees, being more severe on cultivars Barton, Desirable, Wichita, and Mahan. By early 2016, the disease was distributed throughout the state. Symptoms began in late spring on mature leaves as round, reddish-brown spots with a dark halo, measuring 0.5 to 1.5 cm in diameter, and progressed to cause severe defoliation by late summer. Pure cultures were obtained through single-spore isolation from young, reddish-brown leaf spots on 'Barton' from an orchard in Anta Gorda (RS). The spores were plated on carrot agar medium (200 ml carrot juice, 20 g agar, 800 ml distilled water) and incubated under continuous light at 20°C for 56 days. Colonies formed brown creeping aerial mycelium with light brown conidiophores, usually singly but sometimes in fascicles, measuring 95 × 4 μm with prominent, thickened, and darkened conidiogenous loci. Conidia were light brown, often curved, smooth, tapered toward the distal end, with 0 to 21 septa, and measuring 20 to 157 × 2.75 to 5 μm, with a thickened and darkened hilum at the base. Morphological characteristics fit the description of Sirosporium diffusum (Heald & F. A. Wolf) Deighton (Ellis 1976). A partial region of tef1-α gene and the ITS region were amplified using the primers EF1 and EF2 (O'Donnell and Cigelnik 1997) and ITS1 and ITS4 (White et al. 1990), respectively. Although there were no previous sequences of this fungus deposited in GenBank, both ITS and tef1-α sequences were 100% identical to the respective unpublished sequences of a culture of S. diffusum currently deposited at the CBS-KNAW collection (CBS 106.14). The sequences of our isolate were deposited in GenBank (accession numbers KX344494 and KU534938, respectively). A pathogenicity test was performed to fulfill Koch's postulates. Twenty detached mature leaflets of 'Barton' were inoculated each with 100 µl of spore suspension (2 × 105 spores ml–1), divided into six drops, and distributed separately on the adaxial leaf surface. Twenty detached mature leaflets were used as controls and were treated with distilled water. The leaflets were maintained in sterile plastic boxes with two moistened sheets of filter paper at 23 ± 1°C and a 12-h photoperiod. The test was repeated three times. The original disease symptoms were observed on the inoculated leaves after 9 days, but not on the control leaves. Subsequently, the pathogen was reisolated from the lesions and identified as S. diffusum. This is the first report of S. diffusum causing brown leaf spot on C. illinoinensis in Brazil. The identification of this pathogen will allow the study of strategies for managing the disease in Brazil.References:Ellis, M. B. 1976. More Dematiaceous Hyphomycetes. CMI, Kew, Surrey, U.K. Crossref, Google ScholarO'Donnell, K., and Cigelnik, E. 1997. Mol. Phylogenet. Evol. 7:103. https://doi.org/10.1006/mpev.1996.0376 Crossref, ISI, Google ScholarWhite, T., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego. Crossref, Google ScholarDetailsFiguresLiterature CitedRelated Vol. 101, No. 2 February 2017SubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Issue Date: 13 Jan 2017Published: 14 Nov 2016First Look: 11 Oct 2016Accepted: 3 Oct 2016 Pages: 381-381 Information© 2017 The American Phytopathological SocietyCited byDiagrammatic scale for quantifying severity of brown leaf spot on Carya illinoinensis1 January 2020 | Anais da Academia Brasileira de Ciências, Vol. 92, No. suppl 1Mycosphaerellaceae : Chaos or clarity?Studies in Mycology, Vol. 87, No. 1
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